There is a formula that can be used to predict the amount of space required for any given database.
Following is a description of the variables and their respective descriptions:
|D||The expected number of documents in a content database|
|The average size of the documents to be stored|
|L||The number of list items (roughly three times the number of documents|
|V||The number of retained version for a document; the default value is 1 for the document|
|M||The estimated amount of metadata (a constant of 10 KB that can be adjusted if your environment is more metadata-intensive|
An estimate for size of any given content database is the given by this formula